Liquid heating device

ABSTRACT

The device for heating liquid generates steam, receives a fluid in liquid form at its inlet, and ejects the fluid heated up or in gaseous form at its outlet. The device includes a heater positioned inside a sleeve having a longitudinal axis. There is a scraper that fits onto the heater to scrape it the heater in case of movement along the longitudinal axis. A stopper fits snugly between the heater and the sleeve in order to stopper the passage. The scraper, the stopper, and a spring are configured so that an increase in pressure causes the scraper and the stopper to move along the longitudinal axis so that the stopper is shifted to a point where space between the heater and the sleeve allows fluid to pass, and a reduction in pressure causes a shift in the opposite direction by the spring.

RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention falls within the field of heating of liquid, in particular heating of water, and generation of steam.

The invention is related in particular, but not restrictively, to the field of electrical household appliances such as iron, coffee maker and the like, as well as to household or industrial appliances for cleaning a surface by steam sputtering.

Such devices will find a preferred application in the framework of cleaning and degreasing of surfaces, for example, non-restrictively, of textiles, walls or windows, or also in the domestic setting, namely for uncreasing textiles.

As is known, such a device transforms the water contained in a steam tank by heating, with putting or not under pressure, so as to expel the steam through a conduit to an opening, usually provided with a nozzle.

The present invention is related more generally to any field of heating of fluid, in particular water, and steam generation.

2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.

There are already known devices for heating water, which also permit to generate steam. They generally include a heating resistor placed in an external cover, or heating body, which is in the form of a sleeve. Water is then caused to enter under well-adjusted conditions from an upstream side between the outer sleeve and the heating resistor. The water is heated in contact with the resistance, then turns into steam before exiting in the form of vapor from the downstream side.

A first drawback of these devices resides in that the hot-water flow-rate depends on the water-supply rate and the heating capacities of the resistor. It should be noted that it is possible to cope with this drawback by causing the liquid to flow inside the heating body in a non-rectilinear way from upstream to downstream, which is achieved by creating hindrances inside the heating body. However, such a design has limits, in particular in that these hindrances are applied against the wall of the heating body, which is expensive, or they are arranged centrally, which involves arranging the resistor inside the heating body, with a loss of performance.

Another drawback of the steam generators resides in the fouling of the heating resistors, namely with limestone contained in the water. As the limestone is accumulated on the heating resistor, the heating efficiency decreases, and after a time of operation, the heating is not sufficient to turn water into steam. Or the flow-rate of incoming water and therefore of the steam produced must be reduced in an unacceptable way. The device must then be disassembled and the resistor cleaned. Moreover, when limestone has accumulated, it is not easy to remove it.

It should be noted that it is known, from EP 0,514,271 for example, to wind on a resistor an element capable of moving relative to said resistor, according to the movement of the liquid, so as to carry out a scraping of said resistor. However, the effectiveness of such an assembly is very poor, because the scraping is very limited, since it depends on the mobility of the wound element, in the longitudinal direction and in axial rotation.

SUMMARY OF THE INVENTION

The present invention pretends to cope with the above-mentioned drawbacks, providing a solution permitting to improve the performances of heating of a liquid at a very low cost, and in an evolution of this solution, the possibility of automatically cleaning the heating resistor, thus making it operational for a much longer time.

To this end, the invention relates to a device for heating a liquid, in particular water, comprising a heating means with a cylindrical external shape arranged within a sleeve having a longitudinal axis. The word “cylindrical” is understood here in the mathematical meaning, that is, the cross-section in a plane perpendicular to the longitudinal axis is identical along this axis, whereby this cross-section may further be of any shape, in particular circular, rectangular, square or the like.

The device is particular in that it internally includes, inserted over the heating means, in the space separating the latter from the internal surface of the sleeve, an element designed capable of creating disturbances in the flow of fluid in said space.

The device is also particular in that the element designed capable of creating disturbances in the flow of fluid has the functions of a scraper adjusting onto the heating means so as to scrape it in case of a movement along said longitudinal axis, a stopper, closely fitting between the heating means and the sleeve so as to close its passage in at least one position of said stopper, and a spring, said scraper, stopper and spring being configured such that an increase of the pressure of the entering fluid generates a movement along said longitudinal axis of the scraper and the stopper so as to move said stopper to a point where the space between the heating means and the sleeve is such that it allows said fluid to pass, and that a decrease in the pressure of the entering fluid generates a displacement in the opposite direction thanks to said restoring spring. Thanks to these provisions, the heating means is periodically cleaned in a fully automatic way.

According to further features :

-   -   said scraper can be configured to scrape both the external         surface of the heating means and the internal surface of the         sleeve,     -   said scraper may have a helical shape with non-joining spires,         which permits to allow the fluid to be introduced between the         spires, until it reaches the stopper,     -   said stopper may have a helical shape with joining spires,     -   said scraper and said stopper may be two portions of one single         part, thus simplifying the device,     -   said scraper, said stopper and said spring can be three portions         of one single part, further simplifying the device,     -   said scraper, said stopper and/or said spring can have a         cross-section having the shape of a circular ring in a plane         perpendicular to said longitudinal axis, which facilitates the         manufacture of these or this part ; the shape can also be that         of a rectangular or square ring, or the like,     -   said scraper is in the form of a helical winding of an element         having a rectangular or square cross-section.

In its simplified version, the invention consists in using a simple spring, inserted onto the resistor, so as to cause the flow of fluid to follow a helical path.

In its more complex version with the possibility of scraping, the spring has particular characteristics.

The present invention also relates to a method for automatically cleaning a heating means with a cylindrical external shape using a device according to the invention and comprising the following steps :

-   -   supplying fluid in liquid form     -   heating the fluid up to its vaporization, which increases the         volume of fluid on the inlet side of said device     -   displacement along the longitudinal axis of the stopper and the         scraper, producing a first scraping of the heating means, until         allowing the fluid to pass to the outlet, which generates an         pressure drop at the inlet of the device     -   displacement in the opposite direction of the stopper, until it         is closed, generating a second scraping of the heating means.

Further features and advantages of the invention will become clear from the following detailed description, which refers to an embodiment given by way of an indication and non-restrictively.

BRIEF DESCRIPTION OF THE DRAWINGS

The understanding of this description will be facilitated when referring to the attached drawings.

FIG. 1 represents a schematic longitudinal cross-sectional view of a device according to the invention, in a first position.

FIG. 2 represents a schematic longitudinal cross-sectional view of the device of FIG. 1, in a second position.

FIG. 3 represents a schematic cross-sectional view of the device of FIG. 1.

FIG. 4 represents a schematic cross-sectional view of a device according to the invention, according to a second embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

As shown in FIGS. 1 to 4 of the attached drawing, the present invention relates to a device 1 for heating a fluid, and also for generating steam, comprising a heating resistor 2 arranged in the sleeve-shaped heating body 3 having a longitudinal axis 4. The device 1 is connected at its inlet 5 to a water inlet E, and ejects the water steam V generated at its outlet 6.

It should be noted that the heating element 3 may, in one embodiment, not shown, also incorporate heating means.

The device 1 comprises a helically shaped scraper 7 with non-joining spires, a helically shaped stopper 8 with joining spires, and a spring 9. The fluid, which is water E being gradually transformed into a gaseous state so as to become vapor V, enters through the inlet 5 into the space located between the heating resistor 2 and the sleeve 3. The fluid enters between the spires of the scraper 7 until it reaches the spires of the stopper 8. There the fluid is blocked and cannot go to the outlet 6. Through the effect of heating and vaporization of the water E, the fluid volume increases, and the pressure exerted onto the stopper 8 also increases, causing its displacement toward the outlet 6, while compressing the spring 9. When the displacement is sufficient to allow the fluid to pass (see FIG. 2) the fluid that has become vapor V is discharged to the outlet 6, where said steam V is used according to the desired application. At the same time, on the inlet side 5, since the fluid escaped, the pressure has dropped, nothing pushes the stopper 8 to the outlet 6. The spring 9, which has been compressed, is then released and brings the stopper 8 and the scraper 7 into their initial position, and a similar cycle can start. During each round trip of the stopper 8 through the increase in pressure of the vapor V on the entrance side 5, then through the escape of steam V to the outlet 6 under the action of the spring 9, the scraper 7 cleans the cylindrical external surface of the heating resistor 2 through its longitudinal movement.

The term cylindrical is to be understood here in its mathematical meaning: the external shape of the heating means 2 should be cylindrical in that it has the same cross-section along the whole longitudinal displacement. This can be a circular cylinder (see FIG. 3) or a square cylinder (see FIG. 4) or any other geometrical shape, provided that shape is the same all along the heating means 2, so that when the scraper 7 moves along the longitudinal axis 4 it matches the external shape of the heating means 2 along its displacement.

In the embodiment shown in FIGS. 1 to 4, the cross-section 7 of the scraper completely fills the available cross-section between the heating resistor 2 and the sleeve 3. This embodiment has the advantage that the scraper 7 also cleans the inner face of the sleeve 3 at each of its longitudinal movements. In an embodiment not shown, the scraper 7 can also match the external shape of the heating means 2, but be at a distance from the sleeve 3. The fluid can then pass through the space left free, and abut directly on the stopper 8. Indeed, the fouling, namely by limestone, is much more significant on the hottest surface, which is that of the heating means 2. It can be chosen to implement the automatic cleaning only on that surface, without departing from the scope of the present invention.

The stopper 8 must necessarily close the whole space between the heating means 2 and the sleeve 3, so as to prevent the fluid from passing towards the outlet 6 as long as the movement of the stopper 8, and hence of the scraper 7, towards the outlet 6 has not been performed.

In the embodiment shown, the sleeve 3 is also cylindrical, but longer than the heating means 2, in order to leave a space where the stopper 8 can be accommodated for allowing the fluid to pass. In another embodiment not shown, the sleeve 3 may be widened towards the outlet 6, so that when the stopper 8 arrives in front of the widening of the sleeve 3, the fluid can escape.

Furthermore, in the embodiment shown, the spring 9 has the same outer and inner diameter as the stopper 8 and the scraper 7. In another embodiment, this spring 9 may have a different shape, provided that it performs its function for restoring the stopper 8 into its initial position, which drives the scraper 7, which generates the cleaning of the heating means 2.

The advantage of the present invention resides in particular in that the heating means 2 and, as the case may be, the inside of the sleeve 3 are automatically and periodically cleaned. Limestone has no time to accumulate, and the efficiency of the heating is therefore constant.

It should be noted that, preferably, the scraper 7 consists of a helical winding of an element having a square or rectangular cross-section, so as to have, on the side of the heating means 2, two ridges 70 and 71 and on the side of the sleeve 3, two ridges 72 and 73, which permit to increase the scraping function.

Advantageously and as shown, the scraper 7, the stopper 8 and the spring 9 are portions of one single spring-shaped part inserted onto the heating means and having areas having particular characteristics so as to match these different portions.

Although the invention has been described with reference to a particular embodiment, it is understood that it is in no way limited thereto and that various changes in shapes, materials and combinations of these various elements can be made without thereby departing from the scope and spirit of the invention. 

1. Device for heating a liquid, comprising: an inlet for receiving a fluid; an outlet for ejecting the; a heating means with a cylindrical external shape arranged within a sleeve having a longitudinal axis; an element internally inserted onto the heating means and in space separating the heating means from an internal surface of the sleeve, said element creating disturbances in flow of fluid in said space, said element being comprised of a scraper engaging the heating means so as to scrape the heating means during a movement along said longitudinal axis; a stopper, closely fitting between the heating means and the sleeve, said stopper having a closed position of a passage in at least one position of said stopper; and yet a spring, said scraper, said stopper and said spring being configured such that an increase of pressure of entering fluid generates a movement along said longitudinal axis of the scraper and the stopper so as to move said stopper to a point where space between the heating means and the sleeve allows said fluid to pass, wherein a decrease in the pressure of the entering fluid generates a displacement in the opposite direction thanks to said spring.
 2. Device according to claim 1, wherein said scraper scrapes both an external surface of the heating means and the internal surface of the sleeve.
 3. Device according to claim 2, wherein said scraper has a helical shape with non-joining spires.
 4. Device according to claim 1, wherein said stopper has a helical shape with joining spires.
 5. Device according to claim 1, wherein said scraper and said stopper are two portions of one single part.
 6. Device according to claim 1, wherein said scraper, said stopper and said spring are three portions of one single part.
 7. Device according to claim 1, wherein at least one of said scraper, said stopper and said spring has a cross-section having a shape of a circular crown in a plane perpendicular to said longitudinal axis.
 8. Device according to claim 1, wherein at least one of said scraper, said stopper and said spring has a cross-section having a shape of a rectangular or square crown in a plane perpendicular to said longitudinal axis.
 9. Device according to claim 1, wherein said scraper comprised of a helical winding of an element having a rectangular or square cross-section.
 10. Method for automatically cleaning a heater having a cylindrical external shape using a device according to claim 1, said method comprising the following steps: supplying fluid in liquid form; heating said fluid to vaporization, increasing volume of fluid on an inlet side of said device; displacement along the longitudinal axis of the stopper and the scraper, producing a first scraping of the heating means, until fluid passes to the outlet, generating a pressure drop at the inlet; and displacement in The an opposite direction of the stopper, until said stopper is closed, generating a second scraping of the heating means. 